A massive winter storm that has slammed the Midwest was bearing down on New York City and much of the Northeast Thursday, packing heavy snow, strong winds and frigid temperatures.

Snow began falling overnight in parts of New England and New York, but the real brunt of the storm wasn't expected to hit until later Thursday and early Friday.

The National Weather Service placed the entire New York City area under a winter storm warning for Thursday and Friday. A winter storm warning means severe winter weather conditions are expected or occurring.

Winter storm warnings were also in effect in most of New York State, New Jersey, Massachusetts, Rhode Island, Connecticut and eastern Pennsylvania.

Blizzard warnings were also posted on Long Island and on Cape Cod in Massachusetts.

With 3 to 7 inches of snow forecast for New York city, Gov. Andrew Cuomo urged commuters to leave their cars at home in case major highways are closed for Thursday's evening rush hour.

"We are looking at a serious storm situation," he said.

Some schools in New England and New York closed pre-emptively or planned early dismissals, while cities issued parking bans and homeless shelters were expected to fill beyond capacity.

As of midday Thursday, the Weather Channel was reporting that at least 100 million Americans were under some level of winter storm warning, watch or advisory; the area stretched from southern Indiana to eastern Maine, a distance of almost 1,200 miles.

The network has named the storm Winter Storm Hercules as part of its winter storm naming system, now in its second season.

Up to 14 inches of snow is forecast for the Boston area and the weather service issued a blizzard warning for Long Island - where 8 to 10 inches of snow could fall and winds could gust up to 45 mph - from Thursday evening into Friday afternoon.

Dot Joyce, Boston Mayor Thomas Menino's press secretary, said it was too early to say whether students' first day back to school, slated for Friday, would be canceled. "We are New Englanders - we get snow and we get cold weather and we're hardy," she said.

The powerful storm has already brought over a foot of snow in some spots in the Midwest. Palatine, Ill., has reported the highest snowfall total from the storm so far, with 15 inches, AccuWeather reported, while several other towns north of Chicago also reported more than a foot of snow, according to the Weather Channel.

Authorities said the weather may have been a factor in a fatal crash Wednesday evening involving a pickup and a bus carrying casino patrons in Indiana. Police said the truck's driver was killed and 15 bus passengers were injured in the collision on a snow-covered and slushy highway in Rolling Prairie.

Airports suffering the worst by 2 p.m. are Chicago O'Hare, which had 592 cancellations; Newark, which had 347 cancellations; and Boston, which had 245 cancellations, according to FlightStats.

The storm was expected to dip as far south as Washington, which could get up to 2 inches of snow.

In Toms River, N.J., Jonas Caldwell said he was prepared for whatever the storm might bring

"Santa brought me a snow blower, and I've got rock salt for the ice, so now I'm just waiting for the storm," he said while grabbing a coffee at a convenience store.

Much colder air will roar into the East on Friday, the weather service reported, with many areas seeing temperatures that are some 20-30 degrees below normal. Some record lows are possible.

"This is likely to be the coldest weather for much of the Northeast since January 2009," according to AccuWeather meteorologist Bernie Rayno.

Lows in cities such as Philadelphia, New York and Baltimore will drop into the single digits Friday night while temperatures will drop below zero in Hartford, Conn.; Albany, N.Y.; Providence, R.I.; Portland, Maine; and Boston.

Freeze watches and warnings have been posted all the way down to northern Florida, as temperatures are forecast to plummet into the upper 20s.

Wind chills could dip as low as 19 degrees, prompting the weather service in Jacksonville to warn Floridians that "if you must venture outdoors, make sure you wear a hat and gloves."

And in Green Bay, fans were preparing for a brutally cold NFL playoff game Sunday afternoon between the Packers and the 49ers, when temperatures are forecast to be below zero, with wind chills far below that. Temperatures could rival the famed "Ice Bowl" game of 1967, when the game time temperature was -15 degrees.

Early next week, the weather service predicted that northeast Wisconsin could see its coldest temperatures since February 1996.